It's the centerpiece of Episode 12 of Season 4, called "Blowing Smoke," in which Sterling Cooper Draper Pryce must come to grips with losing the Lucky Strike account.

And, Smith's timing couldn't have been better, since Mad Men returns to AMC on March 25.

Take a look at the letters side by side.

Here's Smith, explaining how he got to this point.

"After 12 years at the firm, first as a summer intern while at Stanford, then in New York for 10 years, and now in London, I believe I have worked here long enough to understand the trajectory of its culture, its people and its identity. And I can honestly say that the atmosphere here now is as toxic and destructive as I have ever seen it."

He goes on, "To put the problem in the simplest terms, the interests of the client continue to be sidelined in the way the firm operates and thinks about making money."

Here's how Draper launches his screed:

"For over 25 years, we devoted ourselves to peddling a product for which good work is irrelevant, because people can't stop themselves from buying it. A product that never improves, causes illness, and makes people unhappy. But there was money in it. A lot of money. In fact, our entire business depended on it."

Says Draper, "We knew it wasn't good for us, but we couldn't stop."

Smith, in his closing paragraphs, drops his resignation bomb. "Goldman Sachs today has become too much about shortcuts and not enough about achievement. It just doesn't feel right to me any more."

He adds: "People who only care about making money will not sustain this firm -- or the trust of its clients -- for very much longer."

Draper's denouement: "So as of today, Sterling Cooper Draper Price will no longer take tobacco accounts. We know it's going to be hard. If you're interested in cigarette work, here's a list of agencies that do it."

He concludes, "As for us, we welcome all other business because we know our best work is ahead of us."

The playwright Tom Stoppard says, "I think theater ought to be theatrical." And as it turns out, resigning from Goldman Sachs can be, too.